JP6975580B2 - Press molding method - Google Patents

Description

The present invention relates to a press molding method.

In press molding by drawing, a blank material is pressed to stretch the material to form a vertical wall portion, and a predetermined three-dimensional shape is formed. For example, panel parts and the like of an automobile body are often molded by the above-mentioned press molding (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-27902

In the method of pressing the blank material by drawing to form the vertical wall portion as in Patent Document 1, the blank material is stretched to form the vertical wall portion, so that the material is on the side of the vertical wall portion by that amount. Inflow to. Therefore, in order to obtain a molded product having a desired size, it is necessary to use a large blank material in consideration of the above-mentioned inflow amount, and there is a problem that the yield is deteriorated.

Therefore, it is an object of the present invention to provide a press molding method capable of reducing the inflow amount of a material into a vertical wall portion and molding using a smaller amount of material.

In order to solve the above problems, the present invention is a press forming method for pressing a plate material by moving a die relative to a punch to form a convex bent portion having a vertical wall portion on the plate material . In a state where the end side is sandwiched from both directions in the pressing direction, an overhanging step of forming a convex overhanging portion inward of the sandwiched portion of the plate material, and after the overhanging step, the end of the plate material. With the punch and the die in a state where the portion side is sandwiched from both directions in the press direction and the bending start position of the overhanging portion is arranged inside the punch in a direction orthogonal to the press direction. the sheet was pressed by, saw including a diaphragm forming the convex bent portions on the inner side of the clamped portion of the plate, nip pressure applied to the plate in the overhanging step, the in the drawing step It is characterized by being larger than the holding pressure applied to the plate material.

According to such a configuration, the blank material is overhanged to form an overhanging portion before drawing. As a result, the blank material can be thinly stretched in advance to form a bent shape without changing the overall width of the blank material, so that the inflow of the material into the vertical wall portion during drawing can be reduced.

According to the present invention, since the inflow of the material into the vertical wall portion during drawing can be reduced, the desired product can be molded with a smaller blank material, and the yield can be improved.

It is sectional drawing of the overhanging processing apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the state which the overhanging processing apparatus sandwiched a blank material. It is sectional drawing which shows the state at the time of the overhanging process. It is sectional drawing which shows the state after the overhanging process. It is sectional drawing of the drawing processing apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the state which the drawing machine sandwiches an intermediate material. It is sectional drawing which shows the state at the time of drawing. It is sectional drawing which shows the state after drawing. It is a figure which shows the distribution of the thickness of a molded product. It is sectional drawing which shows the intermediate material of the shape different from this embodiment. It is sectional drawing which shows the processing apparatus of a different embodiment. It is sectional drawing which shows the state which the processing apparatus sandwiches a blank material. It is sectional drawing which shows the state after the overhanging process by a processing apparatus. It is sectional drawing which shows the state which the 2nd movable part was lowered. It is sectional drawing which shows the state which the overhanging part was deformed. It is sectional drawing which shows the state which the 1st movable part and the 2nd movable part were lowered. It is sectional drawing which shows the state after drawing processing by a processing apparatus.

In the press molding method of the following embodiment according to the present invention, for example, a door inner panel which is an automobile part can be molded. Each step of the press forming method of the present embodiment is performed through an overhanging step, a drawing step, a punching step, a pulling bending step, and a hole punching step. In the present embodiment, among the above steps, the overhanging step and the drawing step will be described in particular.

FIG. 1 shows a cross-sectional view of the overhanging apparatus 10 used in the overhanging process.
As shown in FIG. 1, the overhanging apparatus 10 mainly includes a die 11, a punch 12, a blank holder 13, and a base 14.

The die 11 is provided so as to be able to move up and down with respect to the punch 12. The die 11 has a pressing surface 11a and a forming surface 11b recessed from the punch 12 with respect to the pressing surface 11a on the side facing the punch 12. The pressing surface 11a is provided in a circumferential shape so as to surround the molding surface 11b. The molded surface 11b is a concave portion having an arcuate cross section.

The punch 12 is fixed to the base 14. The punch 12 has a convex arcuate forming surface 12a corresponding to the forming surface 11b on the side facing the die 11.

The blank holder 13 is provided in a circumferential shape so as to surround the punch 12. The upper surface 13a of the blank holder 13 functions as a mounting surface on which the blank material 50 is placed and also functions as a pressing surface for pressing the peripheral edge of the blank material 50. The blank holder 13 is provided so as to be able to descend with respect to the base 14 by applying a load from the die 11.

Hereinafter, the overhanging process of the blank material 50 using the overhanging processing apparatus 10 will be described with reference to FIGS. 1 to 4. It should be noted that the thickness of the blank material varies due to the overhanging process and the drawing process described later, and is not uniform. However, in the following figure, the thickness is assumed to be constant for convenience.

First, as shown in FIG. 1, the peripheral edge of the blank material 50 is placed on the upper surface 13a of the blank holder 13.

Then, by lowering the die 11 with respect to the punch 12, the pressing surface 11a abuts on the peripheral edge of the blank material 50 from above, as shown in FIG. As a result, the blank material 50 is sandwiched by the pressing surface 11a of the die 11 and the pressing surface 13a of the blank holder 13 with a predetermined cushion pressure. In the overhanging process, by setting this cushion pressure large, the edge portion of the blank material 50 is sandwiched at this position so that the entire width of the blank material 50 does not change before and after the overhanging process.

In this state, by further pushing down the die 11, a force in the pushing direction acts on the blank holder 13. As a result, the die 11 and the blank holder 13 are integrally lowered with respect to the base 14 and the punch 12 while sandwiching the peripheral edge of the blank material 50. Then, as shown in FIG. 3, the lower surface on the center side of the blank material 50 is pressed against the molding surface 12a and receives a force to push it relatively upward, and gradually projects toward the die 11. After that, as the die 11 is pushed down and reaches the bottom dead center, the intermediate material 60 having the overhanging portion 61 on the central side is formed as shown in FIG. The overhanging portion 61 has an arcuate cross section and has a gentler curvature than the convexly bent portion of the molded product after drawing, which will be described later.

As described above, the peripheral edge of the blank material 50 is sandwiched by the high cushion pressure, so that the overhanging portion 61 is formed without changing the total length of the blank material 50. That is, by the above-mentioned overhang molding, the overhang portion 61 is formed by stretching mainly the central side of the blank material 50 thinly, and the central side of the intermediate material 60 is thinner than the edge side.

Next, a cross-sectional view of the drawing apparatus 20 used in the drawing step is shown in FIG.
As shown in FIG. 5, the drawing apparatus 20 mainly includes a die 21, a punch 22, a blank holder 23, and a base 24.

The die 21 has a pressing surface 21a and a forming surface 21b recessed from the punch 22 with respect to the pressing surface 21a. Further, the punch 22 has a molding surface 22a on the die 21 side.

Further, similarly to the above-mentioned overhanging apparatus 10, the die 21 is provided so as to be able to move up and down with respect to the punch 22, and the punch 22 is fixed to the base 24. Further, the blank holder 23 is provided so as to be able to descend with respect to the base 24 by applying a load from the die 21.

Hereinafter, drawing of the intermediate material 60 using the drawing device 20 will be described with reference to FIGS. 5 to 8.

First, as shown in FIG. 5, the intermediate material 60 formed by the above-mentioned overhanging process is placed on the upper surface 23a of the blank holder 23.

Then, by lowering the die 21 with respect to the punch 22, the pressing surface 21a abuts on the peripheral edge of the intermediate member 60 from above, as shown in FIG. The die 21 and the blank holder 23 sandwich the intermediate material 60 with a predetermined cushion pressure by the pressing surface 21a and the pressing surface 23a. In the drawing process, this cushion pressure is set smaller than that in the overhanging process. Therefore, the total width of the intermediate material 60 is variable before and after drawing. Further, the height of the overhanging portion 61 is provided lower than the height of the convex bending portion 71 (see FIG. 8) of the molded product described later, so that the overhanging portion 61 is formed on the molding surface 21b of the die 21 in the state of FIG. Is non-contact.

By further pushing down the die 21 from the state shown in FIG. 6, a force in the pushing direction acts on the blank holder 23. As a result, the die 21 and the blank holder 23 are integrally lowered with respect to the base 24 and the punch 22 while sandwiching the peripheral edge of the intermediate material 60. Then, the lower surface of the overhanging portion 61 is pressed against the molding surface 22b of the punch 22 from the edge side thereof.

As this descent further progresses, the upper surface on the center side of the overhanging portion 61 is pressed against the molding surface 21b of the die 21. As a result, as shown in FIG. 7, the overhanging portion 61 is crushed by the molding surface 21b of the die 21 and the molding surface 22b of the punch 22, and the intermediate material 60 is gradually moved from the edge side to the center side. It is pressed against the molding surface 22a and the drawing process proceeds. Then, when the die 21 reaches the bottom dead center, as shown in FIG. 8, a press-molded product 70 having a convexly bent portion 71 on the center side is formed.

For example, when the blank material 50 is directly drawn to form the molded product 70, the material is stretched and flows into the vertical wall portion 72 due to the formation of the vertical wall portion 72, and the overall width thereof is reduced. .. However, in the present embodiment, since the material on the center side of the blank material is thinly stretched to form a bent shape by overhang molding, the material flows into the vertical wall portion 72 when the vertical wall portion 72 is formed by drawing. The amount can be kept small. Therefore, the width of the blank material required to obtain the desired molded product 70 is reduced, and the yield can be improved.

In the present embodiment, in the longitudinal direction of the blank material 50 (molded product 70), the vertical wall portion 72 is formed on the edge side of the position where the overhanging portion 61 of the intermediate material 60 is formed, and the vertical wall portion 72 is formed. Is provided on the edge side of the overhanging portion 61 with respect to the rising portion. Therefore, the overhanging portion 61 is formed by stretching the material on the center side of the vertical wall portion 72 thinly without reducing the wall thickness of the portion forming the vertical wall portion 72 as much as possible. That is, in the present embodiment, the overhanging portion 61 can be formed without impairing the wall thickness of the portion for forming the vertical wall portion 72 as much as possible, and the inflow of the material into the vertical wall portion 72 during drawing processing is suppressed as much as possible. Can be done.

By the way, in the door inner panel that can be molded in the present embodiment, the peripheral edge and its vicinity correspond to the frame portion of the panel, and the central side is a so-called offal portion having attachment portions and openings for other parts. The rigidity of such a door inner panel can be ensured by providing a certain thickness or more on the peripheral side thereof, and even if the central side is relatively thin, the effect on the rigidity of the product is small. In this respect, in the present embodiment, the material on the center side of the blank material 50 is thinly stretched to form the overhanging portion by the overhanging process as described above. That is, by applying the molding method of the present embodiment to the molding of the door inner panel, the material on the center side, which does not require a wall thickness, can be used as the wall thickness of the vertical wall portion 72, so that the strength of the member is reduced. The yield of the material can be improved with almost no occurrence.

FIG. 9 is a diagram showing an example of the thickness distribution of each part of the molded product 70. The dotted line part is a conventional molded product obtained by only drawing a blank material, and the solid line part is the molding of the present embodiment. Indicates the product. As shown in FIG. 7, in the molded product 70, the wall thickness on the peripheral side is thicker than the wall thickness on the central side. Further, the wall thickness of the molded product 70 is the thinnest at the portion of the vertical wall portion 72. There is a difference in the wall thickness on the center side between the molding method of the present embodiment and the conventional molding method, and the molding method of the present embodiment has a thinner wall thickness on the center side. It can be seen that the molding method of the present embodiment can reduce the unnecessary wall thickness on the center side and improve the yield by that amount.

In the present embodiment, the shape of the overhanging portion of the intermediate material is a convex arc shape as shown in FIG. However, the present invention is not limited to this, and the beat shape may be as shown in FIG. 10 (a), or as shown in FIG. 10 (b), the overhanging portion is provided only around the position corresponding to the vertical wall portion of the product. It may be a configuration that is partially provided.

The shape of the overhanging portion as described above can be formed by overhanging by changing the shapes of the molding surface 11b of the die 11 and the molding surface 12a of the punch 12 shown in FIG. 1 to corresponding shapes. It is possible to further improve the yield by selecting the optimum shape of the overhanging portion according to the shape and arrangement of the vertical wall portion required for the desired product. In the case of the bead-shaped overhanging portion, the amount of stretching of the blank material due to the overhanging can be greatly increased, so that the height of the overhanging portion is smaller than that of the shape of one mountain. In this way, the optimum height of the overhanging portion is selected in consideration of the amount of material to be flowed in, the shape of the overhanging portion, and the like.

After the drawing process, the molded product 70 is completed through a predetermined process such as cutting an unnecessary portion in the punching process and then forming a predetermined bent portion or opening in the pull-bending step and the hole punching step. It is molded as a product.

In the above-mentioned overhanging apparatus 10 and drawing apparatus 20, each processing is performed by raising and lowering the die with respect to the punch. On the contrary, the structure is such that the punch is raised and lowered with respect to the punch. You may.

Further, in the above embodiment, the case where the overhanging apparatus 10 and the drawing processing apparatus 20 are separately provided and the overhanging processing and the drawing processing are performed by each processing apparatus has been described. However, the press of the present invention is performed by a single processing apparatus. A molding method can also be implemented.

For example, as shown in FIG. 11, the processing apparatus 30 of the present embodiment mainly includes a die 31, a punch 32, a blank holder 33, and a base 34.

The die 31 is provided so as to be able to move up and down with respect to the punch 32. The die 31 has a pressing surface 31a and a forming surface 31b recessed from the punch 32 with respect to the pressing surface 31a on the side facing the punch 32.

Further, the die 31 has a movable portion 31c that can be raised and lowered relative to the main body portion of the die 31, and an accommodating portion 31d that can accommodate the movable portion 31c. The movable portion 31c and the accommodating portion 31d are provided in a circumferential shape and are provided so as to surround the shape of the overhanging portion described later.

The punch 32 has a fixed portion 32a, a first movable portion 32b, and a second movable portion 32c. The fixed portion 32a and the first movable portion 32b are formed in a hollow cylindrical shape, and the first movable portion 32b is provided inside the fixed portion 32a, and the second movable portion 32c is provided inside the first movable portion 32b. It has a structure. The second movable portion 32c is formed in a cylindrical shape.

The fixing portion 32a is fixed to the base 34. Further, the first movable portion 32b and the second movable portion 32c are provided so as to be relatively movable with respect to the fixed portion 32a and the other movable portions, respectively. The fixed portion 32a has a molding surface 32a1 on its upper surface, the first movable portion 32b has a molding surface 32b1 on its upper surface, and the second movable portion 32c has a molding surface 32c1 on its upper surface.

The blank holder 33 is provided in a circumferential shape so as to surround the punch 32. The upper surface 33a of the blank holder 33 functions as a mounting surface on which the blank material 50 is placed, and also functions as a pressing surface for pressing the peripheral edge of the blank material 50. The blank holder 33 is provided so as to be able to descend with respect to the base 34 by applying a load from the die 31.

Hereinafter, each step of the press molding method of the present embodiment using the above-mentioned processing apparatus 30 will be described with reference to FIGS. 11 to 17.

First, as shown in FIG. 11, the blank material 50 is placed on the mounting surface 33a of the blank holder 33. In this state, the movable portion 31c of the die 31 protrudes from the accommodating portion 31d, and the lower surface of the movable portion 31c and the pressing surface 31a are flush with each other.

Then, by lowering the die 31 with respect to the punch 32 and the base 34, as shown in FIG. 12, the lower surface of the pressing surface 31a and the movable portion 31c and the pressing surface 33a press the peripheral edge of the blank material 50 to a predetermined cushion. Hold it with pressure. In the overhanging process, the cushion pressure is set large so that the total length of the blank material 50 does not change before and after processing.

In this state, the first movable portion 32b and the second movable portion 32c of the punch 32 are raised with respect to the die 31 and the blank holder 33. As a result, the molding surface 32b1 and the molding surface 32c1 are pressed against the lower surface of the blank material 50, and the blank material 50 gradually projects from the center side thereof to the die 31 side. Then, as shown in FIG. 13, when the first movable portion 32b and the second movable portion 32c reach the top dead center, the intermediate member 60 having the overhanging portion 61 is formed. Since the second movable portion 32c is provided with a larger protrusion amount than the first movable portion 32b, the overhanging portion 61 is formed in a convex shape protruding toward the center side of the intermediate material 60 toward the die 31 side. Will be done.

Then, as shown in FIG. 14, the second movable portion 32c is lowered to a position where the molding surface 32c1 is at the same height as the molding surface 32b1 on the punch 32. Further, in the die 31, the movable portion 31c rises with respect to the main body of the die 31 and is accommodated in the accommodating portion 31d. In this state, the lower surface of the movable portion 31c and the molding surface 31b are flush with each other. After molding the overhanging portion 61, the holding pressure (cushion pressure) of the intermediate material between the pressing surface 31a and the pressing surface 33a is reduced, and the overall width of the intermediate material 60 is variable.

In this state, by lowering the die 31 with respect to the punch 32, as shown in FIG. 15, the lower surface of the intermediate material 60 is pressed against the forming surface 32b1 and the forming surface 32c1, and the upper surface of the overhanging portion 61 is formed. It is pressed against the surface 31b. As a result, a rising portion is formed on the edge side of the intermediate member 60, and the overhanging portion 61 is crushed to reduce its height.

Next, as shown in FIG. 16, the first movable portion 32b and the second movable portion 32c are lowered and housed in the fixed portion 32a, and the molding surface 32b1 and the molding surface 32c1 are at the same height as the molding surface 32a1. The molded surface 32d is formed. By further lowering the die 31 in this state, the lower surface of the intermediate material 60 is pressed against the molding surface 32d, and the upper surface of the intermediate material 60 is pressed against the molding surface 31b (and the lower surface of the movable portion 31d) to perform drawing. Be given. Then, as shown in FIG. 17, when the die 31 reaches the bottom dead center, the molded product 70 having the convexly bent portion 71 having the vertical wall portion 72 is molded.

As described above, in the present embodiment, it is not necessary to provide separate processing devices for the overhanging process and the drawing process, and both processes can be performed by one processing device. Therefore, there is no need to change the mold, and the blank material can be overhanged and drawn more quickly.

Further, in the above-mentioned processing apparatus 30, the shape of the overhanging portion 61 of the intermediate material 60 can be arbitrarily changed by changing the amount of protrusion of each movable portion and the number of movable portions to be divided (two in the present embodiment). Can be done. Thereby, the optimum shape of the overhanging portion 61 can be selected according to the distribution of the required wall thickness of the molded product and the like. Also in this embodiment, by changing the corresponding shape of the processing apparatus, the shape of the overhanging portion can be changed as appropriate, such as the shape of the beat in FIG. 10 (a) and the shape of FIG. 10 (b). Of course.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

In the present embodiment, for the sake of simplification of the description, the case of molding a molded product having a shape having one convex bending portion has been described, but it is possible to similarly mold a molded product having a plurality of convex bending portions. Of course.

10 Overhanging equipment 20 Drawing equipment 30 Processing equipment 11, 21, 31 Die 12, 22, 32 Punch 13, 23, 33 Blank holder 14, 24, 34 Base 50 Blank material 60 Intermediate material 61 Overhanging part 70 Molded product 71 Convex Bent part 72 Vertical wall part

Claims (1)

In a press forming method in which a plate material is pressed by moving the die relative to the punch to form a convex bent portion having a vertical wall portion on the plate material.
An overhanging step of forming a convex overhanging portion inward of the sandwiched portion of the plate material in a state where the end side of the plate material is sandwiched from both directions in the pressing direction.
After the overhanging step, the bending start position of the overhanging portion is arranged inside the punch in a state where the end side of the plate material is sandwiched from both directions in the pressing direction and in a direction orthogonal to the pressing direction. while being, the sheet was pressed by said said punch die, saw including a diaphragm forming the convex bent portions on the inner side of the clamped portion of the plate,
A press molding method characterized in that the holding pressure applied to the plate material in the overhanging step is larger than the holding pressure applied to the plate material in the drawing step.

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